Telegraph apparatus



4 Sheets-Sheet 1 Inventor $4 MM Attorney July 22, 1941. F. WARBURTONTELEGRAPH APPARATUS Filed June 19, 1939 x m 1 n m m m r mm July 22,1941.

F. WARBURTON TELEGRAPH APPARATUS Filed J une' 19, .1939

4 Sheets-Sheef2 Inventor WM 'III by W444 3. M Attorney July 22, 1941. wu -i'o 2,250,143

TELEGRAPH APPARATUS Filed June 19, 1939 4 Sheets-aheet s In venlor b 24a). 4M

A ltorney July 22, 1941.

F. WARBURTON TELEGRAPH APPARATUS Filed June 19, 1959.

Fig. 4.

4 Sheets-Sheet 4 I rwenlor A tlorney Patented July 22, 1941 Fre dwarburtcn, London, England, assignoi' to Cable and Wireless. Limited,London, England;

a British company 7 Application june 19, 1939, Serial No. 279,951 InGreat Britain June 23, 1938 (01. us -s3) 23 Claims.

Telegraph receiving apparatus is generally provided with mechanismarranged to undergo cyclic movements at a frequency substantially equalto the speed at which signal elements are received. If a signal elementof a given character,

for example, a marking element, is effective in a cycle, the apparatusis operated to perform a function in that cycle corresponding to thesignal element received. This function may be the perforation of tape,or the setting of a teleprinter permutation member, or the actuation ofa retransmitting device, in accordance with the nature of the signalelement received. This element may, if the apparatus is arranged tooperate under the control of cable Morse code, be either a positive or anegative current impulse.

As is well known, signal elements may be considerably distorted uponreaching receiving apparatus. The distortion is usually least at thecentre of each element, and for that reason it is best to arrange themechanism undergoing cyclic movements to perform its selecting functionto be controlled in accordance with the character of a signal element atan instant occurring at the centre of the corresponding cyclic movement.However, it is possible for the signal elements to become out of phasewith the cyclic operation of the receiving apparatus, and in that event,the mechanism may fail to respond to a received signal element. 4

It is the object of the present invention to provide apparatus which, inthe event of a received signal element being seriously out of phase withthe receiving apparatus, maintains the effect of the received elementfor a sufficient period to enable it to become efiective in the nextcycle.

According to the invention, telegraph receiving apparatus is providedwith mechanism arranged to undergo cyclic movements at a frequencysubstantially equal to the speed at which signal elements are receivedfor determining at two instants in each cyclic movement whether a signalelement of a given character is in transit at those instants andarranged to control means for retaining the effect of the signal elementduring the next cyclic movement if the signal element is in transit atone of the instants but not at the other. Thus, even when a block signalis received, that is a number of consecutive elements of the samecharacter or kind, i. e. marking elements, without an interveningspacing element, each of the consecutive elements, including the last,is effective; The said mechanism forms part of or is arranged to move intimed relationship with the mechanism which takespart in the performanceof functions in accordance with received signal elements.

Advantageously, the instant occurring first may be substantially at thecentre of each cyclic movement while the second instant occurssubstantially at the end of such movement, the ap paratus beingarrangedso thatif the element is in transit only at. the second instant, theeffect of the element is maintained during 'the next cyclic movement.Thus, it will be seen that if an element is not. effective at the firstinstant, the apparatus. is in condition to retain the effect of an.element provided that element arises at the second instant. The reasonfor determining whether or not a signal element is in transit at bothinstants is that, if the apparatus was set to retain the effect. of amarking element, 1. e. a signal element of the given character,according to whether or not such signal element was in transit only atone instant, the means for retaining the effect of the element would beoperated by spacing elements and there would be no distinction betweenmarking and spacing conditions.

Conveniently the mechanism may also be arranged to control the phaserelationship between the said cyclic movements. and the said incomingsignals. Then, if a signal element is slightly out of phase with thecorresponding cyclic movement, the necessary adjustment is madautomatically so that ensuing elements are substantially in phase withthe cyclic movements. It will be understood that provided the phaserelationship is only slightly out of adjustment, it is only necessary tocorrect th phasing because, in spite of the slight lead or lag of anelement in relation to its corresponding cyclic movement, the element isstill received at a time which enables the associated function to beperformed in that cyclic movement. When, however, the element is sobadly out of phase that the function cannot be performed in thecorresponding cyclic movement, the aforesaid means for retaining theeffect of the element becomes operative so that the correspondingfunction is performed in the next cyclic movement and the means forcontrolling the phase relationship may thereafter become effective tomaintain an ensuing, element properly timed in relation to the cyclicmovements of the mechanism.

In order that the invention may be clearly understood and readilycarried into effect, apparatus in accordance therewith will now bedescribed, by way of example, with reference to the. accompanyingdrawings, in which:

Figure 1 is a perspective view of certain parts of the apparatus;

Figure 2 is a diagram for use in explaining the operation of theapparatus;

Figure 3 is a diagram of an electrical circuit under the control of theapparatus shown in Figur 1; and

Figure 4 is a further circuit diagram showing apparatusused inassociation with the apparatus of Figures 1 and 3;

Referring to the mechanism of Figure 1, this includes a shaft l whichmay be regarded as part of, or in driven engagement with, the main shaftof a telegraph receiving apparatus. The latter may, of course, be aretransmitter or it may be arranged to print characters or perforatetape in accordance with received signals. The shaft l' rotatescontinuously during the operation of the receiving apparatus and makesone complete revolution for each signal element received. When themechanism is incorporated in the telegraph printing apparatusparticularly described in my British Patent specifications Nos. 463,975,463,976 and 463,977, the shaft I would form part of or be geared to theshaft 84 of those specifications. 1 The mechanism can be arranged foroperation under the control of cable Morse code, double current cablecode or Wheatstone Morse code, and will be described in relation tocable Morse code, in which the signal elements are of three difi'erentkinds, namely, a spacing or nocurrent element, a positive markingelement and a negative marking element. The positive and negativeelements represent respectively dots and dashes, or vice Versa.

Fixed to. the shaft l are four eccentrics 2a, 2b, 2c and 2d, embracedrespectively by rings forming parts of eccentric rods 3a, 3b, 3c, and3d. The eccentrics are set out'of phase relatively to each other so thatthe eccentric rods 3a, 3b,. 3d and 30 rise and fall in succession foreach revolution of the shaft I. The eccentric rods 3a.3d are pivotedrespectively to four levers 4a, 4b, 4c and id, which are mounted toswing independently of each other about a fixed spindle 5. To the freeends of the levers la-4d, are pivoted at 4w, 4m, 4y and 42 respectivelyfour selecting members Ba, 6b, 6c and 6d. These selecting members are inthe iorm'of bell cranks and are formed at the ends of theirsubstantially horizontal parts with downwardly-extending lugs 1a, lb, 10and Id.

For each marking signal element received, i. e., for each positive ornegative element but not for a spacing element, an electromagnetB isenergised to attract an armature 9, the armature being swung about anaxis at its lower end. Each time the armature-9 is attracted, its upperend 9a, bearing against four levers iila, Hlb, Inc and lfld, swings themin an anti-clockwise direction (as viewed in Figure 1) about a fixedspindle II respectively against the action of four wire springs IZa,1222, I20 and |2d which are bent round a fixed rod l3 with their upperfree ends bearing against a fixed stop bar Hi. When the electromagnetbecomes die-energized, the armature 9 can be pushed back by one or moreof the springs l2al2d acting on the levers lai8d. The levers Ilia-19dare associated respectively with four controlling members i5a, i517, Weandl5d, the latter, like the levers |0ailld, being pivoted independentlyabout the spindle l l. The levers l0al0d are formed respectively withthe lateral lugs lEa, 16b, I60 and 1601 from which project respectivelywire springs Ila, Mb, i la and lid, the upper ends of which engageprojections lBa, [8b, I80 and lfld, formed on the controlling membersI5a-I5d. v V

Now consider the action, for example, of the lever lfla When this isswung about the spindle H by the armature 9. The associated controllingmember l5a is also swung about that axis by the action of the wirespring Ila on the projection l8a, the right hand edge (as viewed inFigure 1) of the selecting member We being held by that spring inengagement with the lug. [6a. The

lever Illa and the controlling member i5a, therefore, swing as a unitabout the spindle II. The controlling members I5a-i5d are formedrespectively at their lower ends with lateral lugs I9a, I91), I90, and19d, which co-operate respectively with the lugs 1a-1d of the selectingmem- 'bers .6a5d. Thus, when the controlling member a is swung in ananti-clockwise direction,

its lug lila is moved beyond the right hand edge of the associated lugIa. If the phase relationship between the incoming signal, 1. e. themovement of the armature 9, and the rotation of the shaft l is such thatthe bottom edge of the lug 7a on the selecting member 6a is carrieddownwards, through the medium of the associated eccentric 2a, beyond'thetop edge of the lug [9a after the latter has been swung to the right,the

selecting member 6a will not be interfered with.v

instant when the bottom of the lug la registers with the top of the lugi9a. In the upper part of its travel, the selecting member 6a is heldagainst a fixed rod 2|] by a wire spring 2m fixed to the eccentric rod3a and in engagement with the selecting member 611. There are, ofcourse,

' three further springs Zib, 2lc and 2ld associated respectively withthe selecting members 61), 6c and 6d and arranged similarly to thespring Zia. When the lug la engages the top of the lug [9a, theselecting member 6a swings away from the rod 20, but whenthe lug iSa ismoved to the right, the selecting member Ba lies against the rod 20throughout its reciprocation.

Means are provided for locldng each of the controlling members l5a-i5dinto one or other of its two positions as soon as the correspondingselecting member coacts with it. Associated respectively with theselecting members Baa-6d are four wire springs 21a, 21b, 21c and 27dwhich I are bent round the spindle 5 and at their right hand end bearagainst a fixed rod 29. The left hand ends of these springs Tia-21dco-operate with notches 28a, 28b, 28c and 28d, formed respectively inthe controlling members l5a. These springs rest respectively on thelevers 4ta4d and have a downward bias so that they tend to follow themovements of these levers as they are swung about the spindle 5. theevent of the controlling member l5a, for example, not having been swungin an anti-clockwise direction from the position of Figure 1 at theinstant when the lug la engages the top of the lug Eta, thetip of thespring 21a will have moved downwards with the lever to so far as toengage the right hand edge of the controlling member l5a','beneath thenotch 28a, to prevent the controlling member l5a from being swung to theright by the engagement of the lever 10a by the armature 9. Thus, assoon as the selecting member 611 has explored the position of thecontrolling member I5a, the latter is locked in its left hand positionuntil the selecting member 5a has Accordingly, in

the lug |9a and out of contact therewith, the left hand tip of thespring |8a is raised opposite the notch 2811 so that the controllingmember |5a can be swung in an anti-clockwise direction, the tip of thespring 21a then entering the notch 28a. When this condition arises, thecontrolling mem ber 5a is held against returning in a clockwisedirection as soon as the right hand edge of the lug'la overlaps the lefthand face of the lug I31: and cannot return until the selecting member6a has been raised suiliciently for the lug 7a to :clear the lug i9a,even although the electromagnet8 may already have become de-energized.So long as the lug la overlaps the lug |9a the spring 21a, being engagedby the bottom edge of the notch 28a, does not follow the lever Ea.

Accordingly, when the armature 9 is attracted in a period when the lugla is engaging the top of the lug Mia and the controlling member |5a isheld against movement in an anti-clockwise direction by the tip of thespring 210. engaging beneath the notch 23a, the armature movement is notheld up because the lever lila can still be swung in an anti-clockwisedirection while the spring I la yields and the lug |6a swings away fromthe controlling member I5a.

Switch levers 24a, 24b; 24c and 24d are pivoted independently upon aspindle 25 and are under the action respectively of wire springs 26,26b, 26c and 2601, each of which is bent over the spindle 25 and, at oneend, engages its respective switch lever and, at the other end, thefixed rod 29. These springs tend always to hold the switch levers 2ia2ddup against a fixed rod 30. They can, however, be held away from the rod30 by latch levers 39a, 30b, 39c and 30d pivoted on a fixed spindle 3|and urged clockwise about this spindle respectively by wire springs 32a,32b, 32c and 32d, each of which is bent over the spindle 3| and, at oneend, engages its respective latch lever and, at the other end, a fixedrod. 33. When the switch levers Z ta-24d are in their uppermostpositions, the latch levers rest behind lugs 34a, 34b, 34c and 3403 onthe switch levers 24(1r-24d.

Now, consider the switch lever 24a when in the position shown in Figure1, that is, when in its uppermost position. If the selecting member 6a,in moving downwards, is not affected by the lug |9a on the controllingmember |5a (the latter being in its right hand position), 2. lug 22a onthis selecting member engages a lug 23a on the switch lever 24a, so thatthe latter is depressed, being swung in an anti-clockwise directionabout the spindle 25. The switch lever 24a is depressed in this mannersufficiently for the lug 34a thereon to pass beneath the level of ashoulder 30w formed on the associated latch lever 39a. The latter isthus freed to be moved a little in a clockwise direction by the spring32a, so that the lug 34a is held beneath the' shoulder 39w. Accordingly,when the selecting member 6a is raised again, the switch lever 24a doesnot follow it but is held in its lowermost position by the latch lever39a.

In the alternative condition, when the switch lever 24a. is unlatchedand the selecting member 6a is swung in a clockwise direction about itspivot 4w as a result of the engagement of its lug 1a with the lug l9a,the lug 22a on the selecting member 6a traverses a path such that itpasses to the right hand side of the lug 23a. Therefore, the switchlever 24a is not depressed. Supposing, however, that the switch lever24a has been depressed and is held in its lowermost position by thelatch lever 39a, then, in the next reciprocation of the selecting member6a, the latter has no eifect on the latched switch lever 24a if the lug|9a is in its right hand position so as to permit the selecting member6a. to remain in contact with the rod. 20. On the other hand, if, inthis next reciprocation, the lug la engages the top of the lug 9a sothat the selecting member '6a is swung clockwise about its pivot 4w, anose 35a at the upper end of the selecting member engages the left handedge of the latch lever 30a and swings the latter anti-clockwise torelease the switch lever 24a to its uppermost ;-posi-- tion. It will beseen, therefore, that if the selecting member 6a is swung clockwiseabout its pivot 4w, the switch lever 24a is allowed either to remain inits upper position or is caused to return to its upper position. In theother condition, when the selecting member 6a, remains against the rod20, the switch lever 24a is either forced downwards to its lowermostposition or, if already there, is allowed to remain in that position.

The actuation and effect of the selecting members 6b, 6c and 6a isprecisely the same asthat described above in respect of the selectingmember 6a. The selecting members 6b, 6c andwfid are formed respectivelywith noses 35b, 35c .and 35d and with lugs 22b, 22c and 22d in preciselythe same Way as the selecting member 6a. Further, the switch levers 24b,24c and 24d are formed with lugs 34b, 34c and 34d corresponding to thelug 34a. These lugs co-operate with shoulders 30x, 30 and 302 on theirrespective latch levers 30b, 30c and 30d in the same way as the lug 34aco-operates with the shoulder 39w. However, only the switch levers 24band 2411 are formed with lugs 23b and 23d similar to the lug 23a. Thelug 230 for the switch lever 2-40 is not formed on that member but isformed-on a member 36 which is under the control of the latch lever30?).

The latch lever 39b is formed with a substantially horizontal extension301: which carries a leaf spring 3'! extending through a slot in a lug38 forming part of a bell crank lever 39 pivoted on a spindle 40. A jaw4| is formed at the lower end of the 'bell crank lever 39 and a lug 42formed on the member 36 passes loosely through this jaw. The member 36is formed at its upper end with a slot 36a: through which the spindle 49passes. Therefore, when the latch lever 30.b:is turned about the spindle3|, the bell crank lever 39 is turned about the spindle 49 by the leafspring 31. The member 36 is caused by the jaw 4| to partake of thisswinging movement, but, by virtue of the slot 363: and the slidingengagement between the jaw 4| and the lug 42, the member 36 can movelongitudinally relatively to the bell crank 39, so that the lug 23crests on the top of the switch lever 240 in all positions of the bellcrank lever 39. When the latch lever 3|Jbis in its latching position,the lug 230 is withdrawn to a position in which it cannot be engaged bythe lug 220 but, when the latch lever 3% lies in its right handposition, the position of the lug 23c corresponds to that of the lugs23a, 23b and 2302.

The control of the switch lever 240 is, therefore, unlike the control ofthe other three switch levers in that it depends, not only upon :themovement of the selecting member 60, but also upon whether the lug 23ais in the position to be engaged at all by the lug 22c.

The switch levers 2411-2411 :are formed "respectively with arms 59a,50b, 50c and 59d, whichrespectively operate four switches a, b,=c'-and'd,. shown diagrammatically in Figure 3. These switches havespring contacts, and when the switch levers 24w-24dare all in theiriuppermost or unlatched positions, -the contacts occupy the positionsrelatively to each other shown by full lines in Figure 3, so that nocircuit is completed through a battery or 'other source of electriccurrent and either of 'twoelectromagnets' 53and 54 when a cam I19 on theshaftI is holding spring contactsIBO and -IBI together. Theseelectromagnets are associated with apparatus for momentarily speeding'up or momentarily slowing down the shaft I. Such apparatus is shown inBritish Patent specification No. 238,622, and the shaft 3 in thatspecification may be regarded as corresponding to the shaft I in thepresent specification, while the electromagnets 28 and 29 in this priorspecizfication correspond to the electromagnets 53 and 54 in-Figure 3.When any of the switches a, b, cand d are in the condition shownin fulllines in Figure 3, they can be referred to as being intheir-normal.condition'. When the switch a is changed from its normalcondition to its operated condition by the depression of the switchlever 24a, a contact 43y engages a contact 4310, while a contact 432 isseparated from a contact 4311:. Similarly, when the switchb is operateda contact My is changed over from a contact 44:1: to a contact 44w,while a contact Mr is changed over from a contact 44s to a contact 4412.In similar circumstances in the switch 0, a contact 45; is changed overfrom a contact 4511 to a contact 45w, while a contact '45:: is pressedupon a contact 452. When the switch d is operated a contact 45;! ischanged over from a contact 4550 to a contact 46w. Thus, in each switchthe movable contact or each movable contact is changed over to thedotted line position (Figure 3)- when the switch is-operated. In Figure2 the ordinates represent instants of time'in revolutions of the shaftI. Thus, the instant c occurs at the end of one revolution of the shaft,while the instant c defines the fin-' ish of the next revolution of thatshaft. Further, the ordinates a, b, c and 03 represent the instants inthe last mentioned revolution of the shaft I at which the selectingmembers 6a--6d 'are'caused by their respectiveeccentrics 2a,2d toco-operate with the switch levers 24a,24d either to latch them up or tounlatch them or to leave them where they are. It will be seen,therefore, that it is at these instants that the mechanism of Figure 1differentiates between marking and spacing conditions. It will alsobeseen that the selecting instant 2) occurs when the shaft I hascompleted one half of its revolution, while the selecting instants a'andcl occur justbefore and just after the instant b. The instant 0 occursjust as the shaft completes a revolution. To enable the selectinginstants a and d to be adjusted relatively to the selecting instant b,the eccentrics 2a and 2d are formed on' collars 210 and 20: secured tothe shaft I by set screws 2y and 22. The adjustment is effected byloosening these set 'screwsjturn'ing the collars on the shaft 'I,and'then'tightening the set'screws. The eccentrics 2b and ZCEIGfiXEdpermanently 180 apart.

Furthermore, it will be seen that Figure 2 represents two' furthercycles of the shaft I, respectively defined between the pairs ofordinates c and c, c and c".

- and that between i! and c.

. Now, as indicated above, a circuit can only be closed through one ofthe electromagnets 53 and 54 when the cam I19 is holding the contactsI-I8I together. The cam I19 is so formed as to close these contacts fora period beginning just after the instant d in one cycle and ending justbefore the instant a in the next cycle. Thus, the periods during whichthe contacts I80 and IBI are closed are represented in Figure 2respectively by the space up to the ordinate an, that between y and m,that between 11 and :12" So far as the electromagnets 53 and 54 areconcerned, it is only during these periods that the condition of theswitches a, b, c and al need be considered, because itis only then thata circuit can be closed through battery 5| and one of theelectromagnets.

In ideal working conditions each marking signal element would bereceived substantially in phase with one revolution of the shaft I andwould extend substantially over the period occupied by that revolution.However, line conditions are often such that signal elements do notarrive in phase with the receiving apparatus, and signal elements oftenbecome considerably shortened in transit. First, however, let themarking element represented in the line I-I in Figure 2 be considered,this element being fairly nearly in phase with the revolution of theshaft I represented by the space between the ordinates 0 and c and beingof a length substantially equal to the time taken for that revolution.Thus, the armature 9 is attracted by the electromagnet 8 (Figure 1)before the instant represented by the ordinate a and remains attracteduntil an instant occurring between the ordinates c and a. The result isthat each of the switch levers 24a, 24b and 24d is moved to its latchedposition when its associated selecting instant occurs. On the otherhand, the switch lever 240 is left unlatched because when the lug 22carrives in position to engage the lug 230, the latter will have beenremoved to its inoperative position by the prior movement of the latchlever 30b to its latching position. Accordingly, throughout the periodrepresented between the ordinates y and 0:, when the contacts I80 and NHare closed, the switches a, b and d are in their operated conditionwhile the switch 0 is in its normal state. Thus, the movable contacts inthe switches a, b, and d are in the dotted line positions in Figure 3while the movable contacts in switch 0 are in the full line positions.Therefore, when the contacts I80 and I8I are closed by the cam I19, nocircuit is completed through either of the electromagnets 53 and 54 andno retardation or advance of the shaft I is brought about. This, ofcourse, is what is required because the marking element is sufficientlyin phase with the shaft I.

'It is, in fact, the relationship between the incoming marking elementand the instant b that is important because it is at that instant thata'function, to be performed in accordance with the incoming element, isdetermined by the element. In telegraph receiving apparatus working inaccordance with cable Morse code there are two relays, one of which isoperated upon receipt of a dot element and the other upon receipt of adash element. The energization of either of these relays conditionsassociated mech anism to be operated, by a member undergoing cyclicmovement in timed relationship with the shaft I, to perform a function.This function may be the perforation of tape, or the setting of ateleprinter permutation member, or the setting of'a retransmitter relayarmature in accordance with the dot ordash element received. Now thereceived marking element may be shortened between the transmitter andreceiver and if the element is in phase with the shaft I, the mosteffective part of the element will probably arrive substantially at theinstant b. It is for thatreason that the member moving in timedrelationship with the shaft I is arranged to cause the mechanism toperform the function at the instant b in the centre of the associatedrevolution of the shaft I. The marking element may, of course, arrive solate that it misses the instant b entirely and it is a particularfeature of the invention to provide for such a condition but adescription of this. will be deferred until the signal represented bythe line IIIIII is dealt with.

Returning now to the signal condition represented by the line I--I, itwill be seen that, even if the marking element is shortened by theamount indicated by the dotted line 11. the instant b is still wellwithin the scope of the marking element and the switch condition is thesame as that described above, because the switches a, b and d are intheir operated condition at the instant y. i

Now, suppose that a marking element following a spacing element arrivessomewhat late in relation to the associated revolution of the shaft I(represented by' the space between the ordinates 0 and c) as indicatedby the line IIII, the selecting instant a occurs before the arrivalofthe first part'of the marking element, that is before the armature 9' isdrawn up by the electromagnet 8. However, the armature 9 is drawn upbefore the selecting instant I) has occurred. As the selecting instantsoccur, therefore, the switch lever 24a. is not latched up, being left inits raised position, but the switch levers 24b and 24d are depressed andlatched. Thus, when the cam I19 closes the contacts I86 and I 8| at theinstant y, the switches b and (1 only are operated, so that the movablecontacts in the switches b and d are in the dotted line positions(Figure 3) while the movable contacts in the switches a and care in thefull line positions. A circuit is, therefore, completed from the'battery 5|,

through contacts I80and' IBI, contacts 46y and 4610 in switch d,contacts 43.2 and Mrs in switch (1, contacts My and 4420 in switch I),electromagnet 53, back to battery 5|. When the instant 0arrives'there'is no change in the condition of the switches because theswitch lever 24c cannot be latched owing to the lug 230 being in itsinopera-' the period represented between the ordinates It will be seenthat this is necessary beand at. cause the instant 1) occurs dangerouslynear the beginning of the signal element and not suifi ciently near thecentre thereof. The momentary slowing down of the shaft I results in theselecting instants in respect to the next revolution of the shaft Ioccurring somewhat later than would otherwise be the case. The movementOf the shaf of phase with the incoming signals.

i distant transmitter pass.

I is, therefore, brought more into the correct time relationship'withthe next signal element and the selecting instant I) for that elementoccurs nearer the centre thereof. Speakingin the terms of Figure 2, allthe ordinates to the right of the ordinate c are moved further totheright. It may be mentioned that, even if the marking element shown inthe line IIII is shortened to the extent'shown by the dotted line m,similar conditions obtain because, between the ordinates y and :c', theswitches b and d, but not the switches a and c, are in their operatedcondition. Now consider the case shown by the line III-III where amarking element, following a spacing element, arrives so late inrelation to the corresponding revolution of the shaft I that it missesthe instant b but begins before the instant d; Then, when the instantarises at which the cam I19 closes the contacts I and I 8| only theswitch d is operated. Therefore, a circuit is completed from battery 5|,through contacts I80 and NH, contacts 46; and' ISw in switch d, contacts432 and 43.1: in switch a, contacts 44g and 44x in switch I), theelectromagnet 54, back to the battery 5|. Accordingly, the electromagnet54 is energised, and not the electromagnet 53, so that the shaft I isspeeded up or advanced to bring the selecting instants in the nextrevolution of the shaft I still further out The reason for this is thatwhen a signal element is so late that it misses the instant b, theapparatus is arranged to have its effect in the revolution of the shaftI following the revolution in which the beginning of the signal isreceived. -Th1'1s,th'e function to be performed in accordance with themarking element in the line IIIIII is determined at the instant b whichis brought somewhat nearer the leftthan is shown in Figure 2, andconsequently nearer the centre of the marking element by the advancingof the shaft I. The, marking element may,- however, be shortened sothat, in spite of the advancing of the instant b, the marking elementdoes not overlap that instant. The marking element may, in fact, beshortened as much as is shown by the dotted line 0. It is thereforenecessary to provide means for retaining the effect of the markingelement untilthe instant 'b' and it is one of the functions ofthe switcha to control the maintenance'of a marking element when its phaserelationship with the movements of the shaft I is'substantially as shownby the lineIII-III. Referring again to that line it will be seen that 1the switch c is operated at the instant c owing to the fact that thelatch lever 30b is in its unlatching position so that the lug 230 isinterposed beneath the lug 220 on the selecting lever 60 so as to enablethe latter to depress the switch lever 240. In this connection it may berepeated that the switch lever 240 is only operated when the latch lever30b is in its unlatching position as a result of no marking elementbeing in transit at the instant I).

The operation of the switch 0 at the instant c has no effect on thecircuit which has been completed through the electromagnet 54 whichremains energised until the circuit is broken by the action of the camI19 at the instant :r'.

The closing of the contacts 451: and 652 in the switch c connectsconductors 62 and 63 which are incorporated in the receiver circuit asshown in Figure 4. Referring to the latter, a relay 64 is the line relaythrough which the signals from a This relay has an armature 65 whichtakes up the central position shown when a no-current condition obtains,as in spacing signal elements. When a marking element'of one kind, e. g.a dot, is received, the

armature 65 is swung to the left against a con-' tactlifi. This resultsin a circuit being completed through a' source 6'! of electric currentand an electromagnet 68. The latter then draws up an armature 69 so asto complete a circuit through a winding 'IIJ of alocking relay, afunction relay 7 I ,and the current source 61.

A second function relay I2 is operated when the line relay armature isswung to the right against a contact I3, by a marking element of theother kind, e. g. a dash. The armature 65 is thus caused to close acircuit through an electromagnet I4 so that an armature I5 is drawn upand a circuit through a locking relay winding I6 and the functionrelayI2 is closed. The function relays 'II and I2 are the aforementionedrelays which condition associated mechanism to be operated 'by a memberundergoing cyclic movement in timed relationship with the shaft I. Whenprinting telegraph apparatus as-described in Patent No. 2,148,002 is tobe operated under the control of the function relays, the latter actuatethe armatures 45 and 46 in that patent, while the membermoving in timedrelationship with the shaft I is the actuator I in that patent. Theactuatoroperates mechanism for selecting pairs of permutation membersand the aforesaid armatures 45 and 46 take part in the selection of onepermutation member in'each selected pair. The

selection of the permutation members determines the actuation ofmechanism for printing type and the said actuator selects the pairs ofpermutation members under the control of a further armaturewhich' isactuated whenever a marking signal element arises. This armature wouldbe controlled by an electromagnet 'I'I, arranged, asshown by dottedlines in Figure 4 of the present specification, so as to be energisedwhenever the function relay- II or the function relay I2 is energised.It will be seenalso that the electromagnet 8 is energised whenever thearmature. 69 .or the armature I5 is drawn up.

- On the shaft I.is a cam I9 which closes contacts 80 and BI for aperiod during each revolution of the shaft I. This period begins beforethe instant a or a etc. and ends after the instant b or b etc.Therefore, soon after the switch 0 is operated, the contacts 80 and 8|are closed; Returning I to the phase relationship shown in line III-III,it will be seen that the switch 0 is operated'while current is passingthrough thewinding Ill of the left-hand locking relayand through thefunction relay II, that is, while the locking relay winding I0 isattracting an armature 82 against .a" contact 83. Accordingly, as soonas the contacts 80 and 8| are closed, a circuit is completed through asecond winding 84 of the left-hand locking relay. Thus, assuming thatthe signal element is shortened so that the armature E9 is allowed toreturn to its unattracted position before the selecting instant 1)occurs, the function relay 'II will not immediately become de-energisedbut will be maintained in its energised condition. by current passingthrough the contacts 80 and BI, the contacts 459a and 452, the contact83 and armature 82, and the locking relay winding 84, the latter servingto hold the armature .82 against the contact 83 after the locking relaywinding II! has become deenergised. This condition is maintained untilthe cam I9 allows the contacts 80 and 8| to separate, that is, until theselecting instant b has passed. Therefore, the function relay II ismaintained in its energised state long enough to condition theassociated mechanism to be operated, for the performance of the functionassociated with the marking element, in the revolution of the shaft Isubsequent to the revolution in which the first part of the signal isreceived.

When the received signal element is a dash element a similar actiontakes place, but in that case a second Winding 85 of the right handlooking relay maintains an armature 86 against a contact 81, so that thedash relay I2 is maintained energised until the cam I9 allows thecontacts and 8| to separate.

It Will be seen that the locking relays and the parts associated withthose relays constitute the aforementioned means provided for retainingthe effect of a signal element when a condition such ;as that shown inthe line IIIIII arises.

vthe'contacts I80 and I8I, the contacts 46y and Q63: in switch d, thecontacts 451/ and 45w in switch 0, the electromagnet 54 back to battery5|. Thus, again the shaft I is speeded up or advanced so as to bring thesubsequent selecting instants somewhat nearer to the centre of thereceived marking element, that is to say the effect is to shift somewhatto the left the ordinates on the right of the ordinate c in Figure 2.Again the operation of the switch 0 serves to retain the effect of thereceived element until the instant bfleven although the marking elementmay be shortened to the extent indicated by the dotted line 11 appliedto the line IV-IV, in which event the received *marking element wouldnot overlap the instant I).

In the condition shown by the line V-V in Figure 2 a somewhat shortenedmarking element embraces the instants a and b but finishes before theinstant d. Therefore, throughout the period defined between theordinates y and :r' the switches a and b are operated. The switch 0 ofcourse, is not operated because the switch I) is operated. Thus, whenthe cam I19 is closing the contacts I80 and 18!, a circuit is completedfrom the battery 5! through the contacts I8I and I80, the contacts 46and 48a: in the switch (1, the contacts 45y and 4511 in the switch 0 thecontacts 43w and 4311 in the switch a, the contacts Mt and 4411 in theswitch I), the electromagnet 54, and back to battery 5|. Thus, theelectromagnet 54 is energised to advance the shaft I during the periodbetween the ordinates y and m. This serves to bring the subsequentselecting instants more accurately in phase with the incoming signal, asis required by the fact that the instant 1) occurs dangerously near theend of the marking element shown by the line V-V.

It is a particular feature of the apparatus that it is equally effectivewhen block signals are received, that is to say, a series of markingelements in sequence having the effect of a single prolongedmarkingelement. One such block signal is shown in line VI-VI where two markingelements, each occupying the time taken for a single revolution of theshaft I, are joined together. When the first part of this block signalis received the condition is precisely the same as that described withreference to the signal of the line IV-IV, that is to say that theswitch is operated before the instant at so that the shaft I is advancedslightly. However, when the cam I19 again closes the contacts I80 andI8l at the instant 2/, all the switches a, b, c and d are operated, andthe result of this is that neither of the electromagnets 53 or 54 isenergised. The important fact, however, is that the switch 0 remainsclosed from the instant represented by the ordinate 0 until the instantrepresented by the ordinate 0''. Accordingly, when the end of the blocksignal arrives the effect is retained. The function to be performed bythe second half of the block signal is determined at the instant I), andthe necessity for retaining the effect of the signal through the switch0 and circuits associated therewith, will be appreciated when thepossibility is considered of the second element being shortened asindicated by the dotted line 1;

In the appended claims, the reference to an output circuit in whichsignal impulses are repeated is to be interpreted broadly to apply toany apparatus controlled by the output circuit of the receiving relay,whether it be a printer, 2. retransmitter, or other suitable apparatus.

I claim:

1. In telegraph receiving apparatus, in combination, signal detectingmeans, means for operating said signal detecting means in cyclicmovements at a frequency substantially equal to the speed at whichsignal elements are received and being operative to determine at twoinstants in each cyclic movement whether a signal element is in transitat those instants, and means controlled by said signal detecting meansfor retaining the effect of the signal element 'during the next cyclicmovement if the signal element is in transit at only one of the twoinstants. a i I 2. In telegraph receiving apparatus, in combination, aswitch operating device having two operative positions, a selectingmember, means for causing said member to undergo to-and-fro movement ata frequency substantially equal to the speed at which signal elementsare received, an intermediate member, means for moving said intermediatemember to and from an effective position enabling said selecting memberto move said operating device from one operative position to the second,a second selecting member, means for causing, said second selectingmember to undergo to-and-fro movement at a frequency substantially equalto the speed at which signal elements are received, signal responsivemeans operative to impart a further component of movement to each saidselecting member to modify the path of movement thereof only when amarking signal element is in transit at a predetermined instant in theto-and-fro movement of the member, the predetermined instant in respectof the first-mentioned selecting member occurring later than that inrespect of the second selecting member, and means controlled by thesecond selecting member, when traversing one of its paths, for causingsaid intermediate member to take up its effective position and, whentrav-.

ersing the otherof its paths, to take up its other position, meanscontrolled by the first-mentioned selecting member being operative, whentraversing one of its paths, for causing said switch operating device totake up one of its positions is in its effective position. 7

3'. In telegraph receiving apparatus, in combination, two selectingmembers, means for causing each'of said selecting members to undergoperiodic to-and-fro movement, signal responsive means arranged to imparta further component of movement to each said selecting member to modifythe path of movement thereof only when a marking signal element is intransit at a predetermined instant in the to-and-fro movement of themember, switch operating devices controlled respectively by saidselecting members, each such device having two positions, one of whichis selected by the associated selecting member at each to-and-fromovement of the member in accordance with the path of movement of thatmember, switches controlled respectively by said devices and means underthe control of said switches for adjusting the phase relationshipbetween received signal elements and the to-and-fro movements of saidmembers. 7

4. In telegraph receiving apparatus, in combi--- nation,signal'detecting means, means for operating said signal detecting meansin cyclic movements at a frequency substantially equal to the speed atwhich signal elements are received and being operative to determine,both at an instant occurring substantially at the middle of each cyclicmovement and at an instant substantially at the end thereof, whether asignal element isin transit at those instants, and means controlled bysaid signal detecting means for retaining the effect of the signalelement during the next cyclic movement if the signal element is intransit only at the second of the said instants.

5. In telegraph receiving apparatus, in combination, signal detectingmeans, means forop erating said signal detecting means in cyclicmovements at a frequency substantially equal to the speed at whichsignal elements are received and being operative to determine at twoinstants in each cyclic movement whether a signal element is in transitat those instants, means con trolled by said signal detecting means forretaining the effect of the signal element during the next cycleofmovement if the signal element is in, transit at only one of the twoinstants, and means controlled by said signal detecting means foradjusting the phase relationship between the cyclic movements of saidsignal detecting means and the incoming signals.

6. In telegraph receiving apparatus, in combination, signal detectingmeans, means for operating said signal detecting means in cyclicmovements at a frequency substantially equal to the rate at which signalelements are receivedphase relationship between said instants and eachparticular signal element.

7. In telegraph receiving apparatus, in com-' bination, selectingmembers and means for caus ing said members to undergo cyclic movementsand, when traversing the other of its paths, causes said switchoperating device to take up its other'position when said intermediatemember selecting at a frequency substantially equal to the speed atwhich signal elements are received and with transit at a particularinstant in' such cyclic Y movement, and means for retaining the effectof a signal element under the control of one of said members, and meanscontrolled'by another of said'members, when traversing one only of itspaths, to permit the first-mentioned member to operate said retainingmeans.

8.'In telegraph receiving apparatus, in combination, selecting membersand means for causing said members to undergo cyclic movements at afrequency substantially equal to the speed at which-signal elements arereceived but with phase displacement between the cyclic movements of therespective members, controlling members allocated respectively to theselecting members and arranged to move between two positionscorresponding to marking and spacing signal conditions, means wherebyeach controlling member is effective when in one only of the twopositions to modify the cyclic movement of its associated selectingmember,-signal responsive means for operating said controlling membersbetween their two positions in accordance with incoming signals, meanscontrolled by one'of said selecting members when traversing one of itspaths to retain the effect of a signal element during the ensuing cycleof movement o'f'that member, and mechanism controlled by another of saidselecting members in traversing a particular one of its two paths toprevent said first-mentioned selecting member from operating saidretaining means when traversing either of its paths. I

9. In telegraph'receiving apparatus, in combination, mechanism includingselecting members, means for operating said selecting .members in-cyclicmovements at a frequency substantially equal to the speed at whichsignal elements are received-with phase displacement between each suchcyclic movement, as many switches as there areselecting members arrangedto be controlled by-the selecting members, each switch having twopositions, one allocated to a marking signal condition and the otherallocated to a spacing signal condition, and means responsive toreceivedsignal elements to operate each switch through the medium of theassociated selecting member at a particular instant in the movement ofthat member, means for retaining the effect of a signal element underthe control of one of. said switches, and further means responsive .toreceived signals for preventing said. one switch from being operated ifa marking element is in transit at the instant when the condition of asecond switch is determined.

10. In telegraph receiving apparatus, in combination, signal detectingmeans, means for operating said signal detecting means in cyclicmovements at a frequency substantially equal to the speed at whichsignal elements are received and operative to determine at two instantsin each cyclic movement whether a signal element is in transit at thoseinstants, and means controlled by said signal detecting means forretaining the effect of the signal element during the next cyclicmovement if the signal element is in transitat only one of the saidinstants, said lastmentioned means including a locking relay under 7 thecontrolof a switch, the condition of said locking relay being determinedat the said one of the two instants.

11. In telegraph receiving apparatus'in combination, a plurality ofdriving members mounted for to-and-fro movement, means for impartingto-and-fro movements to said members with phase displacement betweensaid movements and frequencies substantially equal to the speed at whichsignal elements are received, a plurality of selecting membersrespectively pivotally connected to said driving members, meansresponsive to incoming signals and operative to turn each selectingmember about its pivotal connection if a signal element is in transit ata predetermined point in the to-and-fro movement of the associateddriving member, switch operating members allocated respectively to saidselecting members, latch members allocated respectively to saidoperating members, and means including switches operable by saidoperating members for controlling the phaserelationship between saidto-and-fro movements and the receiv'ed signal. elements, and meanscontrolled by said selecting members for successively and selectivelydetermining in which of two positions each operating member shall lie,one such position being a position in which it is held by theassociated. latch member.

12. In telegraph receiving apparatus,- in combination, mechanismincluding two selecting members, means for operating each selectingmember in cyclic movements at a frequency substantially equal to thespeed at which signal elements are received, retaining means under thecontrol of one of said members for retaining the effect of a signalelement, means responsive to incoming signals arranged at -apredetermined instant in the cyclic movement of said one of said membersto operate said retaining means through the medium of said member onlywhen a. signal element is in transit at that instant and when the secondof said members is inoperative, said signal responsive means includingmeans operative at a further instant to render said second selectingmemberoperative if a signal element is in transit at the furtherinstant.

13. In telegraph receiving apparatus, in combination, asignal responsiverelay having an armature, means for causing said armature to take up anoperative position when a marking signal element is received, twoselecting members, means for causing said selecting members successivelyto co-operate with said armature in a period substantially equal to thetime period occupied by a received signal element, and means controlledby said selecting members for retaining the effect of a signal elementfor a controlled period if said armature is in its operative positiononly when the second of said selecting members is in position toco-operate therewith.

14. In telegraph receiving apparatus, in com-. bination, signaldetecting means, means for operating said signal detecting means incyclic movements at a frequency substantially equal to the speed atwhich signal elements are received and operative to determine atinstants in each cyclic movement whether a signal element is in transitat those instants, electrical switches under the control of said signaldetecting means, means for rendering said switches operative only duringa predetermined part of the time occupied by each said cyclic movement,and means responsive to received signals for adjusting the phaserelationship between the received signals and said cyclic movements,said last-mentioned means being under the control of said switches whenoperative.

15. In telegraph receiving apparatus, in combination, a switch operatingdevice having two operative positions, a selecting member, means forcausing said member to undergo to-and-fro movement at a frequencysubstantially equal to the speed at which signal elements are received,an intermediate member arranged to be moved to and from an effectiveposition enabling said selecting member to move said operating devicefrom one operative position to the second, a second selecting member,means for causing said second selecting member to undergo to-and-fromovement at a frequency substantially equal to the speed at which signalelements are received, signal responsive means operative to impart afurther component of movement to each said selecting member to modifythe path of movement thereof only when a marking signal element is intransit at a predetermined instant in the to-and-fro movement of themember, the predetermined instant in respect of the first-mentionedselecting member occurring later than that in respect of the secondselecting member, and means controlled by the second selecting member,when traversing one of its paths, for causing said intermediate memberto take up its effective position and, when traversing the other of itspaths, to take up its other position, means controlled by thefirst-mentioned selecting member, when traversing one of its paths, forcausing said switch operating device to take up one of its positionsand, when traversing the other of its paths, causes said switchoperating device to take up its other position when said intermediatemember is in its effective position, and 'means controlled by saidswitch operating device for retaining the effect of a marking signalelement when said operating device is caused to take up its said otherposition.

16. In telegraph receiving apparatus, the combination of a receivingrelay having an input circuit for receiving signal impulses and anoutput circuit in which signal impulses are repeated, signal detectingmeans, means operated synchronously with the incoming signals forcontrolling said signal detecting means to detect the presence of signalimpulses at different instants in each signal cycle, and signalcontinuing means controlled by said detecting means and being responsiveto receipt of a signal impulse which has been delayed beyond apredetermined point in any cycle for continuing the effect of saiddelayed signal in said output circuit during the next signal cycle.

17. Telegraph receiving apparatus according to claim 16 in which saidsignal continuing means is operative to continue the effect of a signalwhere the receipt of the signal is delayed beyond the midpoint of thesignal cycle.

18. In telegraph receiving apparatus, the combination of a receivingrelay having an input circuit for receiving signal impulses and anoutput circuit in which signal impulses are repeated, signal detectingmeans, means operated synchronously with the incoming signals forcontrolling said signal detecting means to detect the presence of signalimpulses at different instants in each signal cycle, signal continuingmeans controlled by said detecting means and being responsive to thedetection of a signal impulse at an instant during the second half ofthe signal cycle for continuing the effect of said signal impulse insaid output circuit during the next signal cycle, and means controlledby said detecting means and being responsive to the detection of asignal impulse at an earlier instant in said cycle for preventingoperation of said signal continuing means.

19. In telegraph receiving apparatus, the combination of a receivingrelay having an input circuit for receiving signal impulses and anoutput circuit in which signal impulses are repeated, signal detectingmeans, means operated synchronously with the incoming signals forcontrolling said signal detecting means to detect the presence of signalimpulses at four diiferent instants in each signal cycle, the firstinstant occurring during the first half of the signal cycle, the secondinstant substantially at the middle of the cycle, the third instant inthe second half of the signal cycle, and the fourth instant at the endof th signal cycle, means for adjusting the phase between saidsynchronously operated signal detecting means and said incoming signals,and means for controlling said phase adjusting means by said signaldetecting means to change the phase of said signal detecting means inresponse to abnormal signal conditions in said input circuit.

20. Telegraph receiving apparatus according to claim 19 in which thesignal detecting means and phase adjusting means includes means toretard the phase of the phase adjusting means upon receipt of a signalimpulse beginning between the first and second instants and continuingbeyond the third instant.

21. Telegraph receiving apparatus according to claim 19 in which thesignal detecting means and phase adjusting means includes means toadvance the phase of the phase adjusting means in response to a signalimpulse beginning after the second instant and continuing to the end ofthe cycle.

22. Telegraph receiving apparatus according to claim 19 in which thesignal detecting means and phase adjusting means includes means toadvance the phase of the phase adjusting means in response to receipt ofan impulse beginning before the first instant and ending between thesecond and third instants.

23. Telegraph receiving apparatus according to claim 14 in which fourelectric switches are controlled by the signal detecting means inaccordance with the signal conditions at four different instants in eachsignal cycle, the first instant occurring during the first half of thesignal cycle, the second instant at substantially the middle of thecycle, the third instant in the second half of the signal cycle, and thefourth instant at the end of the signal cycle, means for preventingoperation of the fourth switch corresponding to the fourth instant wherethe switch corresponding to the second instant is operated in any si nalcycle, and wherein the phase adjusting means according to claim 14 iscontrolled by the operation of said switches to retard the phase uponoperation of the first switch alone and upon the joint operation of thesecond and third switches in any cycle, and to advance the phase byoperation of the fourth switch singly and by the joint operation of thefirst and second switches or the third and fourth switches in any givencycle.

FRED WARBURTON.

